A novel process for extracting tellurium from the calcine of copper anode slime via continuous enrichment

Copper anode slime is an important source for extracting tellurium. In this study, a novel process for extracting tellurium from the calcine of copper anode slime via continuous enrichment is proposed. First, tellurium in the calcine of copper anode slime is enriched in the replacement residue by oxidative leaching and replacement with copper powder by controlling potential. Second, tellurium in the replacement residue gets further enriched in tellurium concentrate by sulfation roasting and sulfuric acid leaching. Finally, tellurium ingot is prepared from the tellurium concentrate by alkaline leaching and electrowinning. The results indicate that increasing the concentration of hydrochloric acid is beneficial to the leaching of tellurium and copper during the oxidative leaching process, and the leaching rates of tellurium and copper are 72.86% and 99.25%, respectively. In the replacement process, 99.5% of tellurium is replaced when the solution potential is controlled at 279 mV, and tellurium in the replacement residue exists as cuprous telluride. When the calcine of replacement residue is leached by sulfuric acid, the leaching rate of copper is 98.25%, while that of tellurium is only 3.0%. The tellurium content of the tellurium concentrate is 35.58%. In the alkaline leaching of tellurium concentrate, the leaching rate of tellurium is 97.5%. Tellurium ingot, with a purity of 99.99%, is produced from leaching solution by purification and electrowinning. The purity reaches the No.1 standard in YS/T222-1996 of China. The process achieves efficient extraction of tellurium from copper anode slime by continuous enrichment. (C) 2020 Published by Elsevier Ltd.